1. Field of the Invention
The present invention relates to a thermal power plant in which arrangement and structure of plant components are improved, and particularly to a thermal power plant including a 2 pass-type boiler having a low-rise structure in which a furnace and a rear heat recovery area are continuously arranged in parallel.
2. Description of the Related Art
Thermal power plants including a 2 pass-type boiler are widely used because these plants have a higher earthquake-resistance strength and can be constructed with lower cost in comparison with thermal power plants including a tower-type boiler. In the thermal power plants using a 2 pass type boiler, fuel and air are burned within a boiler, and water is heated by the generated heat to generate steam, which drives steam turbines for power generation. Additionally, they are provided with an air quality control system (AQCS) to purify combustion gas generated by the combustion.
The thermal power plants can use many kinds of fuel, but have a lower efficiency and generate a larger amount of emission of carbon dioxide in comparison with gas turbine combined cycle generators. Then, the efficiency is improved by high temperature and high pressure of steam. However, materials of main steam pipes etc. of thermal power plants, the materials withstanding a high temperature of about 700 degrees Celsius and high pressure of steam, are much more expensive in comparison with typical plant materials. Therefore, it is necessary to minimize an amount of materials used for the high temperature sections.
Conventionally, as described in JP-A No. 2010-43562, an idea that a boiler is buried underground and a main steam pipe that connects the boiler and a steam turbine is reduced in length has been proposed. Additionally, as shown in JP-U No. 64-51704, a 2 output unit type thermal power plant installable even in a small site because a flue and a chimney are arranged along and next to the line of a turbine building and a boiler is disclosed.
In the technology of JP-A No. 2010-43562, when the boiler is buried underground, the construction cost rises, and an additional facility is required to control heat of the boiler. Additionally, JP-U No. 64-51704 discusses an idea about the overall arrangement of a thermal power plant but does not discuss a length of the main steam pipe etc.
The present invention proposes a thermal power plant for achieving high reliability, low material cost, and low construction cost by devising arrangement and structure of a boiler, a steam turbine, and a flue gas treatment apparatus to reduce an amount of a high-temperature resistance material used for a main steam pipe etc. and further by reducing a length and thermal elongation of piping of the main steam pipe etc.